Centuries of folk wisdom, passed down through Katy Perry, tout the benefits of a daily dose of apple cider vinegar. (One of those benefits: emergency pie!)

Hey, Katy Perry seems to be doing really well for herself these days. What's the secret to her success?

Oh, the usual—hard work, talent, a little bit of luck. But also: apple cider vinegar. In an interview with SELF magazine earlier this year, the pop star credited regular doses of Bragg's apple cider vinegar with keeping her energy up and her immune system in great shape.

Isn't that stuff for hippies?

Increasingly, no—this brand of unfiltered ACV, as its fans call it, is increasingly mainstream, beloved not just by celebrities like Katy Perry (for its aforementioned effects on the immune system), Megan Fox ("just cleanses out your system entirely"), Khloe Kardashian ("naturally tones skin, whitens teeth and gets rid of dandruff") and Scarlett Johansson ("natural skincare"), but by plenty of people who make less than a gazillion dollars a year but still toss back a tablespoon or two of ACV on the daily. It's said to be good for heart health and blood sugar levels, and it's one of those things that generations of wise folk have passed down as a sort of all-purpose tonic. (Apple cider vinegar is the base, of course, for fire cider.)

"Some of these things that have been around for decades or centuries and that might seem a little wacky, there's almost always some element of it that probably does have some benefit, which is why people anecdotally have been passing it on forever," says Molly Kimball, a New Orleans-based registered dietician and a columnist for the Times-Picayune.

Are there more concrete dietary reasons to take ACV?

Sure are. Kimball herself actually drinks a couple tablespoons every morning for its "potential alkalizing effects" on acids that form in the body with her protein-rich, exercise-heavy diet—it's thought that the vinegar can offset the kind of acidity that causes joint and muscle pain.

That said, Kimball concedes that the evidence here is largely anecdotal, but points to where it isn't—a little dose of ACV does seem to have positive effects on blood sugar levels. In a 2005 study in Sweden, researchers served varying doses of vinegar to subjects along with a meal of white wheat bread, afterward taking blood samples and testing for glucose and insulin levels, and finding that "the higher the acetic acid level"—acetic acid is what makes vinegar vinegar—"the lower the metabolic responses." This stabilizing effect means it might be helpful for people with diabetes, as well as folks just trying to avoid the spike-crash blood-sugar cycle.

Additionally, subjects who'd gotten that hit of acetic acid reported feeling more full. So while claims of apple cider vinegar "burning fat" are just a bunch of hot air, it may help folks eat a little less.

That Swedish study was about vinegar in general, though.

Well, yes—a bit of a cult has built up around ACV, but there seems to be no particular reason for that. (Bragg's vinegar is unfiltered, meaning that bottles contain a few wispy bits of the mother, which is said, again inconclusively, to have some positive effects on health.) A 2006 roundup of studies on the potential medicinal uses of vinegar doesn't point specifically to ACV but to the entire category, concluding that the strongest evidence points to vinegar's effect on blood glucose, and that various other claims—that it supports heart health, that it can be used as an anti-infective agent—are on shakier ground.

Apple cider vinegar does taste pretty good.

So I should just, like, take a swig from the bottle?

Actually, if you're taking it as a supplement, you'll want to water it down. "You don't want to drink it straight, because it can be very damaging to the lining of your mouth, throat, esophagus, enamel," Kimball says. Stir a couple tablespoons into about eight ounces of water.

What else can it do?

Look, I'm not really a hippie myself, but I am hippie-adjacent, and like all of our people I know the truth: Vinegar is an indispensable household item. It opens drains! It cleans toilets! It dissolves soap scum and hard-water residue. A vinegar solution is great for cleaning out coffee makers and for removing stains. Apple cider vinegar just happens to be one of the cheapest varieties around, which is fine in a salad dressing but could also replace half the bottles stored under the kitchen sink.

But you're still a cooking website, right?

Even in the culinary world apple cider vinegar is a workhorse—after all, it's something people used to flavor pie with when ingredients were scarce. It deglazes pans. It produces flakier doughs. But we've already covered this: